Graduated plug and socket



Sept.y IQTQZS. '1;468,183

J. H, WEATHERLOW ET AL GRADUATED PLUG AND SOCKET Filed March 25. 1921 INVENTORS 3, 5% LW X Patented sept. 18, 1923.

UNITED STATES PATENT OFFICE.

J. HOWARD WEATHERLOW AND FREDERICK W. SEYMOUR, OF FLUSHING, NEW YORK'.

y.GRADUA'IED PLUG AND SOCKET. A

Application led March 25, 1921. Serial No. 455,703.

To all 'whom t may concern.'

Be it known that we, J. HOWARD .IVEATHERIOW and FREDERICK W. SEYMOUR, both citizens ofthe United States, residing at Flushing, in the county of Queens and State 0f New York, have invented certain new and useful Improvements in Graduated VPlugs and Sockets, of which ythe vfollowing is a specification. f

This invention relates to electrical appliances and has particular reference to fusesI or sockets relating thereto.

In our extensive experience in the inspection and installation of electrical appliances we have observed that a very common source of danger lies in the fact that fuse plugs of high capacity are employed in connection with circuits of relatively low capacity, thereby defeating to a large extent the very purpose for which fuse plugs are intended. In other words, in a circuit calculated for carrying a relativelysmall load and guarded by a fuse plug as it should be that will make it impossible for the circuit to be Overloaded and so rendered dangerous, if a fuse plug be employed in said circuit that has suiiicient carrying capacity to sus-k tain an overload on the circuit without blowing or fusing, the circuit is thereby immed, ately rendered dangerous. Accordingly, we have noted.y that fuse plugsv are employed more or less `indiscriminately as to their carrying capacity with referenceto the circuits, and so whether intentionally or not plugs are inserted in place of other plugs- `previously blown out, that are ldangerously.

too heavy for the places or currents into which they are inserted.l Among the objects, therefore, of this invention is to establish and maintain a predetermined correlation between a circuit andV the fuse plug whereby it will be impossible or practically impossible for the circuit to be overloaded because of the use of a plug l of too'high a capacity. p

More specifically, by thls invention it is provided that a plug having a fuse wire calculated for a heavy current cannot be in serted into a socket pertaining to a circuit of low capacity, `although it may be possible for a low capacity plug to be mserted and used in the socket pertaining to a high capacity circuit. ,Y

More specifically we provide a socket or receptacle. comprising one contact which may be similar to that usually employed while the other Contact is adjustable to vary the depth to which the fuse plug may be mtroduced thereinto.

Another object of the invention is to pro- ,vide a fuse plug of predetermined eifective length whereby 0n the introduction thereof. ,lnto the receptacle connection will not be preceding Object, provision is made thaty only fuses of a predetermined capacity may be used. in connection with certain plugs.

A stlll further object of the invention is to provide a renewable fuse including a terminal to which the wire is attached, with' means to prevent accidental dropping out of place of the terminal when the plug is being removed from its receptacle, thereby preventing any possibility of a short circuit at such time.

With the/foregoing and other objects in view the invention consists in the arrangement and combination of parts hereinafter` described and claimed, and while theinvention is not restricted to the exact details of construction disclosed or suggested herein, still for the purpose of'illustrating a practical Vembodiment thereof relerence is had to the accompanying drawings, in which.:

like reference characters designate the same parts in the several views, and in which- Figure 1 is a longitudinal sectional view of one form of our improvement and which may be understood as pertaining ,to al relatively low capacity circuit.

Fig. 2 is a face view of the receptacle, the plug being omitted.

Fig. 3 is a side elevation, partly in section,

ofV a fuse plug adapted for a higher capacity than that Of Fig` 1. y

Flig. 4 is a face view-of the plug shown in'Fig.3.` l

Fig. 5 is a detail view indicating a' plu-'ti rality of selective or graduated fuse wires having not only different capacities but being otherwise distinctive in construction.

Fig. 6 is a detailview indicating one of many means for preventing accidental dropping out of the fuse terminal from the plug.

Referring noW more specifically to the drawings we'indicate a plug 10 comprising a body 11 usually made of porcelain or some other suitable insulating material, the otherwise closed end of the body being provided with a hole' 12 through which the fuse terminal projects. This body is surrounded with a metal shell 13 provided ordinarily with an exterior right handed'thread for (xo-operation with the metal shell 14 of the receptacle. The outer end of the shell 13 consists of a limit flange 15 lying in a plane perpendicular to thevaXis of the body 11 and against which a ring shaped shoulder 16 Iof insulation is threaded by co-operation with the aforesaid exterior thread of the shell 13 and adapted to be locked in such position by suitable means such as screws 17 passing through the flange 15 and into the ring or shoulder 16.

The body 11 of the plug may be' made'of any suitable length or size according to the use for which it is intended, and yet for our purpose the length of all plugs irrespective of the capacity may be substantially uniform while the effective length thereof may be variable according to the thickness of the rings or shoulders 16 as will be appreciated by comparing Figs. 1 and 3. That is to say, in a relatively low capacity equipment the ring 16 will be relatively thin so that the effective length of the plug will be greater than-` in thecase of a high capacity plug whose ring 16 is thicker, making it impossible under ordinary circumstances for the effective length of the high capacity plug to engage the center contact of the lower capacity receptacle.

Again, a further distinction is made between the higher and the .lower capacity plugs in that the fuse wires 18 or 18 thereof are of different sizes or different carrymg capacities and, furthermore, the fusible wire portion is attached` as by soldering or otherwise, to a terminal 19 or 19 that is also distinctive in structure and appearance from the corresponding part of the fuse of any other capacity of fuse plug. As indicated in Fig. 5, for example, the fuse for a heavler capacity plug is provided with a square terminal 19 while the terminal 19 of the lower capacity device is of some other form such.as triangular, so that any one famillar with these devices may know at a. glancethe carrying capacity of the fuse by observing the .heads of terminals. The shank portions also of the terminals are "of dlferent sizes or shapes, and the body por` on of the plug is so made that its hole 12 will receive properly a predetermined size or design of terminal 19. Toreadily adapt these porcelain bodies 11 to the different sizes or shapes of terminals it may be desirable to employ a hollow rivet 20, or its equivalent in the'hole 12, the rivet having a hole therethrough corresponding to the terminal intended for use in 'that particular plug, and the rivet itself may be readily adaptable to the hole 12 even though the casting of the body 11 may not be perfectly accurate in all cases.

The inner end of the fuse wire 18 may be fastened in any suitable manner to the shell 13 of the plug, as in connection with one of the screws 17. A cap 21 of any suitable nature may be connected to the outer end of the plug, as by being threaded upon the periphery of the ring 16. Thus the fuse wire is protected as well as protecting the surrounding property from fire.

When the fuse blows out by the melting of the fuse wire 18 there is ordinarily nothing to prevent the dropping out of the terminal 19 from the hole 12 or hollow rivet. Any suitable mechanical means or device may be provided to prevent this circumstance, and as one means for accomplishing this result we indicate a keeper 22 in the` form of a bent wire embracing the inner end ofthe terminal 19, so that when the plug is removed from its receptacle said terminal cannot drop into the receptacle and cause a short circuit between the two contacts of the receptacle.

The socket or receptacle shown herein comprises any suitable terminals 23 and 2A for the circuit wires, the same being connected respectively with the shell 14 of the socket and the center contact, comprising in this instance a member adjustable longitudinally along the axis of the socket or receptacle. This member is shown as a screw 25 having threaded engagement in a thimble 26 fixed in anysuitable manner in the base 27 of the receptacle. The thimble is provided with a flange 28 shown as holding a washer 29 of insulation in the bottom of the receptacle. The inner end of the ContactJ member 25 is adapted to be engaged by the head of the terminal 19 when the plug is in place, but to accommodate the position of A this center contact to the effective length of vided with aleft handed thread, and so the insertion ofthe plug Will not disturb the position of the screw.

Ve claim:

1. The combina-tion with a receptacle, of a plug co-operating therewith, the plug including an externally threaded shoulder member of a graduatedthickness serving to limit the eiitent of movement of the plug into the receptacle, means to lock the shoulder member with its outer end substantially flush with the outer end of the plug, and a cap threaded upon said shoulder member.

2. In a device of the character set forth, the combination with a receptacle having two normally spaced contacts, and an externally threaded connecting member for said contacts insertable into the receptacle and having a limit flange at its .outer end, of means having threaded connection with the threaded member aforesaid and abutting against said limit flange to govern in accordance with the thickness of said 'means the distance which the connecting member is movable into the receptacle tofefl'ectconnecf tion between the contact members.

3. In a device of the character set forth.

the combination with a receptacle having two normally spaced contacts, of a connecting device insertable into the receptacle for connecting said contacts electrically, one of saidcontacts being adjustable to vary in a f secured in the base and a screw adjustable along the thimble.

5. An electric plug provided flush `with its outer end with an external stop shoulder of graduated thickness to limitl in a predeter- ,mined manner the depth to which the plug may be inserted intoa receptacle.

6. In a plug, a threaded shell having `limit flange` a stop shoulder ring internally threaded to screw onto said shell against said flange, said ring being externally threaded, and a closure for said plug having a threaded portion screwed onto the external threads 0f said ring.

7. A fuse plug comprising a shell having a flange, a'stop shoulder secured against said shell flange at one end and extending therefrom toward the opposite end a measured distance proportioned to limit the insertion of the plug into a socket in proportion to its capacity, said shell act-ing as one contact., a second contact, and a fuse `member connecting said second flange adjacent to the outer end of the stop shoulder.

8. In a plug of the character described, a shell having threads extending from one end to the other and having an outwardly turned flange at its outer end, and a stop shoulder ring formed with internal threads fitting the threads on said shell yand so turned there on as to abut against said flange, and means extending through the said flange into the shoulder to lock the shoulder in place.

In testimony whereof we aflix our` signatures. l l

J. HOWARD WETHERLOW. 'FREDERICK W. SEYMOUR. 

